Gas generator with liquid phase cooling

ABSTRACT

A cylindrical housing has one closed end wall and an opposite end wall provided with an atomizing nozzle and a pair of concentric rows of nozzles encircling the atomizing nozzle. A flexible container within the housing contains a mixture of water and ethyl alcohol. A conduit connects the atomizing nozzle and the container. A charge of propellant material is located within the housing. When the charge is ignited, the hot gases compress the container to force the liquid therein through the conduit and the atomizing nozzle to atomize the liquid. The droplets mix with the hot gases flowing through the concentric rows of nozzles to cool the gases as the gases flow to an inflatable occupant restraint cushion.

United States Patent 1191 1111 3,810,655 Pracher May 14, 1974 [54] GAS GENERATOR WITH LIQUID PHASE 3,483,695 12/1969 Olsen ZZZ/386.5

COOLING Primary Examiner--David Schonberg l [75] mentor (Lake: P PgghglLOYMlgh Assistant Exammer.lohn P. S1lverstr1m [73] Assignee: General Motors Corporation, Attorney, Agent, or Firm-Herbert Furman Detroit, Mich.

[22] Filed: Aug. 21, 1972 [57] ABSTRACT {21] Appl. No.: 282,069 A cylindrical housing has one closed end wall and an opposite end wall provided with an atomizing nozzle and a pair of concentric rows of nozzles encircling the [52] 280/150 35 5 42 2 atomizing nozzle. A flexible container within the hous- 51 I t Cl l ing contains a mixture of water and ethyl alcohol. A i conduit connects the atomizing nozzle and the con- 1 o earc 23 l 4 tainer. A charge of propellant material is located within the housing. When the charge is ignited, the hot gases compress the container to force the liquid [56] References Cned therein through the conduit and the atomizing nozzle UNITED STATES PATENTS to atomize the liquid. The droplets mix with the hot 3,692,495 9/1972 Schneiter et al 141/4 gases flowing through the concentric rows of nozzles 3,091,923 6/1963 Barnes 222/3865 to cool the gases as the gases flow to an inflatable oc- 3,283.962 11/1966 Whitmore.... 222/3 cupam restraint Cushion 3,731,843 5/1973 Anderson 280/150 AB 3,308,818 3/1967 Rutkowski 222/3865 2 Claims, 1 Drawing Figure RESTRAINT RESTRAINT F CUSH ION SENSOR This invention relates to gas generators with liquid phase cooling and particularly to such gas generators intended primarily for use with inflatable occupant restraint cushions.

It is well known to use gas generators for inflation of inflatable occupant restraint cushions. Such gas generators contain a charge of propellant material which is ignitable to generate gases for inflating the cushion. Generally the charge of propellant material consists primarily of black powder although it may be admixed with other materials. The ignition of the gas generator is controlled by either inertia type or acceleration type sensors. The sensors are mounted on the vehicle and are actuated when impact of the vehicle with an obstacle generates an acceleration pulse of predetermined amplitude and time or the vehicle experiences a predetermined change of velocity.

The generated gases are of high pressure and high temperature. Since the gases inflate the occupant restraint cushion, it is well known to mix the propellant gases within the gas generator with either liquid materials or endothermic compounds in order to decrease the temperature of the gases so that the temperature of the cushion remains below a certain limit.

The gas generator of this invention uses liquid phase cooling to cool the high pressure, high temperature gases before the gases flow to the occupant restraint cushion. The mixing occurs exteriorly of the gas generator by the intermixing of the generated gas with atomized liquid. Since the droplets of liquid have a large surface-to-volume ratio, the evaporation rate is greatly increased when the droplets are mixed with the generated gases.

The evaporation rate is important since a high rate of heat transfer must occur between the generated gases and the liquid within a very short time period, such as 30 to 40 milliseconds.

One of the features of this invention is that it provides an improved gas generator with liquid phase cooling wherein high temperature, high pressure gases generated by the ignition of a charge of propellant material compress a flexible container containing liquid to force the liquid through an atomizing nozzle and mix the resultant droplets with the gases flowing from the genera tor to an inflatable occupant restraint cushion to thereby cool the gases. Another feature of this invention is that it provides such a gas generator wherein the atomizing nozzle is encircled by other nozzles through which the hot gases flow to the cushion to ensure a high degree of mixing between the droplets and the hot gases. A further feature of this invention is that the flexible container is axially remote from the atomizing nozzle and communicates with the nozzle through a conduit passing through the charge.

These and other features of the invention will be readily apparent from the following specification and drawing wherein:

The FIGURE is a sectional view of a gas generator according to this invention.

Referring now to the drawing, a gas generator designated generally includes a cylindrical vessel or housing 12 having a closed dome type end wall 14. The axial wall of housing 12 is externally threaded at 16, and an 2 internally threaded cap or housing closure 18 is threaded thereto to close the housing.

The closure 18 includes first and second concentric rows of circumferentially spaced nozzles 20 and 22 which are shown as openings through the closure wall. The nozzles 20 and 22 may be arranged in any pattern, such as in radial alignment with each other or staggered with respect to each other. Any type of removable seal 24, such as tape, normally covers the rows of nozzles. The closure 18 further includes a convergent type opening 26. A suitable pressure rupturable seal 28, such as one of rubber, as shown, or thin metal, closes the opening 26. The seal is staked at 3.0 to the closure.

A flexible container 32 fits within the housing 12 and conforms to the axial wall thereof and the end wall 14 thereof. The container 32 may be made of any suitable material, such as neoprene type rubber, and is filled with liquid 34, such as a mixture of ethyl alcohol and water. I

A cylindrical tube or conduit 36 has the upper end thereof received within a cylindrical axial flange 38 of the closure 18. A swirl nozzle 40 is received within the upper end of the conduit and cooperates with the convergent opening 26 to provide an atomizing nozzle. The neck or outlet 42 of the container 32 receives the conduit and isconventionally clamped thereto at 44 to provide a pressure seal between the container and the conduit. The conduit further includes a number of radial openings 46 which communicate the interior of the conduit with the container 32. The lower end of the conduit opens to the container.

A charge 48 of propellant material, such as conventional black powder with other ingredients, is contained within the housing 12 between the flexible container 32 and the closure 18. As shown, the charge annularly surrounds the neck 42 of the container and the tube 36. A conventional igniter 50 is provided for igniting the charge. The igniter is conventionally connected across a sensor 52 and a source of power.

As is well known in the art of vehicleoccupant'restraint systems, the vehicle includes redundant inertial type sensors or acceleration sensors, or combinations of these, which sense impacts of the vehicle with an obstacle of a magnitude sufficient to generate acceleration pulses of predetermined amplitude and time or predetermined changes in vehicle velocity. When such pulses or changes occur, the sensors actuate the restraint system.

Assuming now that the sensor 52 is actuated due to impact of the vehicle with an obstacle, the charge 48 will be ignited by the igniter 50 to generate volume of high temperature, high pressure gas. The generated gas will flow through the nozzles 20 and 22 and into the schematically indicated manifold 54 which is threaded to closure 18. The manifold conventionally communicates with the inflatable occupant restraint cushion 56. The manifold and cushion are conventional and it is believed that the details thereof are known to those skilled in the art.

The generated gas will additionally act upon the flexible container 32 to compress or squeeze this container so that the liquid 34 will be forced through'theopenings 46' and the lower open end of the tube and upwardly of the tube. As the liquid is forced upwardly of the tube, it will flow through the swirl nozzle 40 an but through the opening and be atomized. The droplets will mix with the hot gases passing through the nozzles 20 and 22 and be evaporated so as to cool the hot gases so that the temperature of the gases flowing to the cushion 56 through the manifold 54 will be below a preset maximum. The container 32 will be collapsed against the tube when all of the generated gas has flowed to the cushion.

Conventionally, the inflator has a time budget of approximately 30 to 40 milliseconds in which to generate the volume of gas. Thus, heat transfer must take place at an extremely high rate in order for the generated gas to be cooled below a certain temperature before the gas inflates the cushion 56. By forcing the liquid 34 through an atomizing nozzle to disperse the liquid into fine droplets, a large surface-tovolume ratio is obtained and this, of course, enhances the evaporation rate and likewise increases the temperature drop in the gases flowing through the nozzles and 22. By dispersing the liquid into fine droplets and by mixing the droplets with the hot gases exteriorly of the gas generator, the gas generator of this invention reduces the temperature of the gas to that desired prior to the time that the gas flows to the cushion 56.

Thus, this invention provides an improved gas generator with liquid phase cooling.

1 claim:

1. A gas generator comprising, in combination, a generally cylindrical housing having end walls, one being provided with an axially located first atomizing nozzle means and an encircling series of radially spaced second nozzle means, a flexible container containing atomizable liquid and located within the housing adjacent the other end wall, conduit means extending axially of the housing from within the container to the first nozzle means, an ignitable charge surrounding the conduit means and located adjacent the one end wall in communication with the second nozzle means, ignition of the charge generating high pressure, high temperature gas within the housing, the gas providing an axial compressing force on the flexible container to force the liquid therein through the conduit means and the first nozzle means and atomize the liquid in droplets, the droplets mixing with the generated gas flowing through the second nozzle means to cool the gas, and means communicating the first and second nozzle means with an inflatable occupant restraint cushion.

2. A gas generator comprising, in combination, a generally cylindrical housing having end walls, one being provided with an axially located atomizing nozzle and an encircling series of radially spaced second nozzles, a flexible container containing atomizable liquid and located within the housing adjacent the other end wall, a conduit extending axially of the housing from within the container to the atomizing nozzle, means sealing the container to the conduit, an annular ignitable charge surrounding the conduit and sealing means and located adjacent the one end wall in communication with the second nozzles, ignition of the charge generating high pressure, high temperature gas within the housing, the gas providing an axial compressing force on the flexible container -to force the liquid therein through the conduit and the atomizing the nozzle and atomize the liquid in droplets, the droplets mixing with the generated gas flowing through the second nozzles to cool the gas, and means communicating the atomizing nozzle and second nozzles with an inflatable occupant restraint cushion. 

1. A gas generator comprising, in combination, a generally cylindrical housing having end walls, one being provided with an axially located first atomizing nozzle means and an encircling series of radially spaced second nozzle means, a flexible container containing atomizable liquid and located within the housing adjacent the other end wall, conduit means extending axially of the housing from within the container to the first nozzle means, an ignitable charge surrounding the conduit means and located adjacent the one end wall in communication with the second nozzle means, ignition of the charge generating high pressure, high temperature gas within the housing, the gas providing an axial compressing force on the flexible container to force the liquid therein through the conduit means and the first nozzle means and atomize the liquid in droplets, the droplets mixing with the generated gas flowing through the second nozzle means to cool the gas, and means communicating the first and second nozzle means with an inflatable occupant restraint cushion.
 2. A gas generator comprising, in combination, a generally cylindrical housing having end walls, one being provided with an axially located atomizing nozzle and an encircling series of radially spaced second nozzles, a flexible container containing atomizable liquid and located within the housing adjacent the other end wall, a conduit extending axially of the housing from within the container to the atomizing nozzle, means sealing the container to the conduit, an annular ignitable charge surrounding the conduit and sealing means and located adjacent the one end wall in communication with the second nozzles, ignition of the charge generating high pressure, high temperature gas within the housing, the gas providing an axial compressing force on the flexible container to force the liquid therein through the conduit and the atomizing the nozzle and atomize the liquid in droplets, the droplets mixing with the generated gas flowing through the second nozzles to cool the gas, and means communicating the atomizing nozzle and second nozzles with an inflatable occupant restraint cushion. 